Green soda glass

ABSTRACT

The invention concerns a colored soda glass of green shade comprising at most 0.27 wt. % of FeO and has under a standard illuminant A and for a thickness of 4 mm, a light transmission (TLA-4) less then 70%, a selectivity (SE4) higher than 1.50 and an ultraviolet radiation transmission (TUV4) less than 20%. Said glass is particularly suited for vehicle side glazing and rear windows.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon, and claims priority from InternationalApplication No., PCT/BE99/00083 filed Jun. 25, 1999, and BelgianApplication No. 9800493 filed Jun. 30, 1998, both of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a green-colored soda-lime glasscomposed of the principal constituents—glass formers—and of coloringagents.

The expression “soda-lime glass” is used here in a wide sense andrelates to any glass which contains the following constituents (inpercentages by weight):

Na₂O 10 to 20% CaO  0 to 16% SiO₂ 60 to 75% K₂O  0 to 10% MgO  0 to 10%Al₂O₃  0 to 5% BaO  0 to 2% BaO + CaO + MgO 10 to 20% K₂O + Na₂O 10 to20%.

This type of glass is widely used in the field of glazing for buildingsor automobiles, for example. It is usually manufactured in the form of aribbon by the drawing or float process. Such a ribbon can be cut intosheets which can then be bent or can undergo a treatment to improve themechanical properties, for example a thermal toughening step.

When referring to the optical properties of a glass sheet, it isgenerally necessary to relate these properties to a standard illuminant.In the present description, 2 standard illuminants are used, namelyilluminant C and illuminant A defined by the Commission Internationalede l'Eclairage (C.I.E.). Illuminant C represents average daylight havinga color temperature of 6700 K. This illuminant is especially useful forevaluating the optical properties of glazing intended for buildings.Illuminant A represents the radiation of a Planck radiator with atemperature of about 2856 K. This illuminant represents the lightemitted by car headlights and is essentially intended to evaluate theoptical properties of windows intended for automobiles. The CommissionInternationale de l'Eclairage has also published a document entitled“Colorimétrie, Recommandations Officielles de la C.I.E. [Colorimetry andOfficial Recommendations of the C.I.E.”] (May 1970) which describes atheory in which the calorimetric coordinates for light of eachwavelength of the visible spectrum are defined so as to be able to berepresented on a diagram having orthogonal axes x and y, called theC.I.E. trichromatic diagram. This trichromatic diagram shows thelocation representative of light of each wavelength (expressed innanometers) of the visible spectrum. This location is called the“spectrum locus” and light whose coordinates are situated on thisspectrum locus is said to have 100% excitation purity for theappropriate wavelength. The spectrum locus is closed by a line calledthe purple boundary which connects the points of the spectrum locuswhose coordinates correspond to wavelengths of 380 nm (violet) and 780nm (red) . The area lying between the spectrum locus and the purpleboundary is that available for the trichromatic coordinates of anyvisible light. The coordinates of the light emitted by illuminant C, forexample, correspond to x=0.3101 and y=0.3162. This point C is regardedas representing white light and consequently has an excitation purityequal to zero for any wavelength. Lines may be drawn from the point C tothe spectrum locus at any desired wavelength and any point lying onthese lines may be defined not only by its x and y coordinates but alsoas a function of the wavelength corresponding to the line on which itlies and on its distance from the point C relative to the total lengthof the wavelength line. Consequently, the tint of the light transmittedby a colored glass sheet may be described by its dominant wavelength andits excitation purity expressed as a percentage.

In fact, the C.I.E. coordinates of light transmitted by a colored glasssheet will depend not only on the composition of the glass but also onits thickness. In the present description, and in the claims, all thevalues of the excitation purity P, of the dominant wavelength λ_(D) ofthe transmitted light and of the light transmission factor of the glass(TLC5) are calculated from the specific internal spectral transmissions(TSI_(λ)) of a glass sheet 5 mm in thickness. The specific internalspectral transmission of a glass sheet is governed solely by theabsorption of the glass and can be expressed by the Beer-Lambert law:

TSI _(λ) =e ^(−E.A) _(^(λ))

where A_(λ) is the absorption coefficient (in cm⁻¹) of the glass at thewavelength in question and E is the thickness (in cm) of the glass. To afirst to a first approximation, TSI_(λ) may also be represented by theformula:

(I ₃ +R ₂)/(I ₁ −R ₁)

where I₁ is the intensity of the visible light incident on a first faceof the glass sheet, R₁ is the intensity of the visible light reflectedby this face, I₃ is the intensity of the visible light transmitted fromthe second face of the glass sheet and R₂ is the intensity of thevisible light reflected by this second face toward the interior of thesheet.

In the description which follows and in the claims, the following arealso used:

the total light transmission for illuminant A (TLA) measured for athickness of 4 mm (TLA4). This total transmission is the result of theintegration between the 380 and 780 nm wavelengths of the expression:ΣT_(λ).E_(λ).S_(λ)/ΣE_(λ).S_(λ)in which T_(λ) is the transmission at thewavelength λ, E_(λ) is the spectral distribution of illuminant A andS_(λ) is the sensitivity of the normal human eye as a function of thewavelength λ;

the total energy transmission (TE) measured for a thickness of 4 mm(TE4) . This total transmission is the result of the integration betweenthe 300 and 2150 nm wavelengths of the expression ΣT_(λ).E_(λ)/ΣE_(λ) inwhich E_(λ) is the spectral energy distribution of the sun at 30° abovethe horizon;

the selectivity (SE) measured as the ratio of the total lighttransmission for illuminant A to the total energy transmission (TLA/TE);

the total transmission in the ultraviolet, measured for a thickness of 4mm (TUV4). This total transmission is the result of the integrationbetween 280 and 380 nm of the expression: ΣT_(λ).U_(λ)/ΣU_(λ), in whichU_(λ) is the spectral distribution of the ultraviolet radiation that haspassed through the atmosphere, defined in the DIN 67507 standard.

SUMMARY OF THE INVENTION

The present invention relates in particular to green glasses. Greenglasses are generally chosen for their protective properties withrespect to solar radiation and their use in buildings is known. Greenglasses are used in architecture and for partially glazing certainvehicles or railroad compartments.

The present invention relates to a highly selective green glass which isespecially appropriate for use in the form of car windows and inparticular as front and rear side windows and as rear window. This isbecause it is important in the automobile field for the windows ofvehicles to provide sufficient light transmission while having an energytransmission as low as possible so as to prevent any overheating of thepassenger space in sunny weather.

Glasses with a high selectivity generally demand a high absorption ofinfrared radiation, which makes them difficult to manufacture inconventional glass furnaces.

The invention provides a green-colored soda-lime glass composed ofprincipal glass-forming constituents and coloring agents, characterizedin that it contains no more than 0.27% by weight of FeO and has, underilluminant A and for a glass thickness of 4 mm, a light transmission(TLA4) of between 40 and 70%, a selectivity (SE4) of greater than orequal to 1.50 and an ultraviolet radiation transmission (TUV4) of lessthan 20%.

The combination of these optical properties is particularly advantageousin that it offers, while ensuring a good light transmission through theglass, a high selectivity value and a low transmission value in theultraviolet. This makes it possible both to avoid internal heating ofthe volumes bounded by windows according to the invention and theesthetically unattractive discoloration of objects placed inside thesevolumes, due to the effect of the ultraviolet solar radiation.

Preferably, the glass according to the invention has a selectivity (SE4)of greater than or equal to 1.55, even more preferably greater than 1.6.Such selectivity values make it possible to optimize the effectivenessof the thermal filtering of a window for a given light transmission andconsequently to improve the comfort within glazed spaces by limiting theextent to which they become overheated when exposed to strong sunlight.

It is remarkable that this result is obtained when the glass has a lowupper limit of the FeO content by weight. This value of the FeO contentmeans that the glass can be produced by means of a conventional furnace,which may be of large capacity. The use of such a furnace is economiccompared with that of small electric furnaces which normally have to beused for the manufacture of highly selective glasses. Indeed in suchcases the high FeO contents make it difficult to melt, sometimesrequiring the use of small-capacity electric furnaces.

Iron is in fact present in most commercially available glasses either asan impurity or introduced deliberately as a coloring agent. The presenceof Fe³⁺ gives the glass a slight absorption of visible light of shortwavelength (410 and 440 nm) and a very strong absorption band in theultraviolet (absorption band centered on 380 nm), whereas the presenceof Fe²⁺ ions causes a strong absorption in the infrared (absorption bandcentered on 1050 nm). The ferric ions give the glass a slight yellowcoloration, whereas the ferrous ions give a more pronounced blue-greencoloration. All other considerations being equal, it is the Fe²⁺ ionswhich are responsible for the absorption in the infrared range and whichtherefore determine the TE. The TE value decreases, thereby increasingthe SE value, as the Fe²⁺ concentration increases. By favoring thepresence of Fe²⁺ ions over Fe³⁺ ions, a high selectivity is thusobtained.

Preferably, the glass according to the invention provides a TL ofgreater than 50%, even more preferably greater than 55%. Consequently,the glass has a light transmission that easily satisfies the lowerlimits recommended for safety reasons at the rear of vehicles.

Advantageously, the dominant wavelength of the glass according to theinvention is less than 550 nm and preferably less than 520 nm. Greenglasses with a shade meeting these upper limits are regarded as beingattractive.

Preferably, a colored glass according to the invention contains no morethan three coloring agents. This is advantageous in terms of the ease ofcontrolling the properties of the batch of components to be melted inorder to produce the glass compared with compositions containing alarger number of coloring agents, the homogeneity of which is moredifficult to maintain.

Preferably, the glass according to the invention contains, as coloringagent, in addition to iron, at least one of the elements chromium,cobalt and vanadium. The addition of very small amounts of theseelements makes it possible to adjust the optical properties of the glassin an optimum fashion and, especially, to obtain a highly selectiveglass.

It is possible to produce a glass having roughly a color similar to thatof the glass according to the invention using, in particular, nickel ascoloring agent. However, the presence of nickel has drawbacks,especially when the glass must be produced by the float process. In thefloat process, a ribbon of hot glass is conveyed along the surface of abath of molten tin so that its faces are plane and parallel. In order toprevent oxidation of the tin on the surface of the bath, which wouldlead to tin oxide being entrained by the ribbon, a reducing atmosphereis maintained above the bath. When the glass contains nickel, this ispartially reduced by the atmosphere above the tin bath, giving rise to ahaze in the glass produced. This element is also unpropitious toobtaining a high selectivity value of the glass which contains it, sinceit does not absorb light in the infrared range, resulting in a high TEvalue. In addition, nickel present in the glass can form the sulfideNiS. This sulfide exists in various crystalline forms which are stablein different temperature ranges, and the transformations of which, fromone form to another, create problems when the glass has to be reinforcedby a thermal toughening treatment, as is the case in the automobilefield and also in the case of certain glazing products for buildings(balconies, spandrels, etc.). The glass according to the invention,which contains no nickel, is therefore particularly well suited to beingmanufactured by the float process and to architectural use or in thefield of motor vehicles or the like.

The effects of the various coloring agents individually considered forproducing a glass are the following (according to “Le Verre [Glass]” byH. Scholze, translated by J. Le Dû, Institut du Verre [Glass Institute],Paris):

cobalt: the Cobalt: the Co^(II)O₄ group produces an intense bluecoloration;

chromium: the presence of the Cr^(III)O₆ group gives rise to absorptionbands at 650 nm and gives a light green color. More extensive oxidationgives rise to the Cr^(VI)O₄ group which creates a very intenseabsorption band at 365 nm and gives a yellow coloration;

vanadium: for increasing contents of alkali metal oxides, the colorchanges from green to colorless, this being caused by the oxidation ofthe V^(III)O₆ group into V^(V)O₄.

The energy and optical properties of a glass containing several coloringagents are therefore the result of a complex interaction between them.Indeed, the behavior of these coloring agents depends greatly on theirredox state and therefore on the presence of other elements liable toinfluence this state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In preferred embodiments, the glass according to the invention hasoptical properties which lie within the ranges defined below:

55%<TLA4<70%

30%<TE4<45%

6%<TUV4<20%

490 nm<λ_(D)<520 nm

2%<P<10%.

The light transmission range thus defined makes the glass according tothe invention particularly useful for reducing the dazzling effectproduced by the light from automobile headlights when it is used for therear side windows or as the rear windows of vehicles. The correspondingenergy transmission range provides the glass with its high selectivity.In the form of front side windows for vehicles, the glass according tothe invention must have a TL of greater than or equal to 70%. It istherefore used with a thickness of 3 mm so as to meet this requirement.As regards the dominant-wavelength and excitation-purity ranges, thesecorrespond to shades and to an intensity of color which are found to beparticularly attractive, especially according to present-day tastes inthe architectural and automotive fields.

These properties are obtained from the following percentages by weightof coloring agents, the total amount of iron being expressed in the formof Fe₂O₃:

Fe₂O₃ 0.7 to 1.3% CaO 0.18 to 0.27% Co 0 to 0.0040% V₂O₅ 0.0050 to 0.1%.

The use of vanadium as coloring agent has the advantage of limiting theproduction costs of the glass according to the invention because of theinexpensive nature of this element. Moreover, vanadium is alsobeneficial in environmental protection terms, due to its less pollutingcharacter, and in obtaining the low ultraviolet radiation transmissionvalue of the glass according to the invention. Vanadium also has a highabsorption in the infrared radiation range, which helps in obtaining aglass having a low energy transmission and a high selectivity.

It is also possible to obtain the same ranges of optical properties fromthe presence in the glass of the following percentages by weight ofcoloring agents:

Fe₂O₃ 0.7 to 1.3% (total iron) FeO 0.18 to 0.27% Co 0 to 0.0040% Cr₂O₃0.0015 to 0.0250%.

The combination of these coloring agents, and in particular the use ofchromium, is not unfavorable for preserving the refractory walls of thefurnace for manufacturing the glass, there being no risk of corrosion ofthe said walls by them.

According to certain especially preferred embodiments, the glassaccording to the invention has optical properties lying within thefollowing ranges:

63%<TLA4<67%

37%<TE4<41%

11%<TUV4<18%

500 nm<λ_(D)<505 nm

4%<P<6%.

Glass having optical properties lying within the more restricted rangesdefined above is particularly efficient since it combines ideal lightand energy-transmission properties for use as the rear side windows andthe rear window of a vehicle. In a thickness of 3 mm, it can also beused as a front side window of a vehicle. In its architectural use, itcombines its esthetic qualities with a considerable energy saving due toless stress on the air conditioning systems.

Such properties are obtained from the following percentages by weight ofcoloring agents, the total amount of iron being expressed in the form ofFe₂O₃:

Fe₂O₃ 0.88 to 0.98% FeO 0.22 to 0.25% Co 0.0003 to 0.0009% V₂O₅ 0.0200to 0.0400%.

It is also possible to obtain the same ranges of optical properties fromthe presence in the glass of the following percentages by weight ofcoloring agents:

Fe₂O₃ 0.88 to 0.98% FeO 0.22 to 0.25% Co 0.0003 to 0.0011% Cr₂O₃ 0.0020to 0.0100%.

Preferably, the glass according to the invention has a percentage byweight of FeO of less than 0.25. This makes it particularly easy to meltin a conventional glass furnace, compared with glasses which havesubstantially higher FeO contents.

The glass according to the invention is preferably used in the form ofsheets having a thickness of 3 or 4 mm for the rear side panes and therear windows of vehicles and thicknesses of more than 4 mm in buildings.

The glass according to the invention also preferably has a total lighttransmission under illuminant C, for a thickness of 5 mm (TLC5) ofbetween 50 and 70%, which makes it favourable to eliminating thedazzling effect of sunlight when it is used in buildings.

The glass according to the invention may be coated with a layer of metaloxides which reduce its heating by solar radiation and consequently thatof the space compartment of a vehicle using such a glass as glazing.

The glasses according to the present invention may be manufactured byconventional processes. In terms of batch materials, it is possible touse natural materials, recycled glass, scoria or a combination of thesematerials. The colorants are not necessarily added in the formindicated, but this manner of giving the amounts of coloring agentsadded, in equivalents in the forms indicated, corresponds to standardpractice. In practice, the iron is added in the form of red iron oxide,the cobalt is added in the form of hydrated sulfate, such as CoSO₄.7H₂Oor CoSO₄.6H₂O, and the chromium is added in the form of dichromate, suchas K₂Cr₂O₇. As regards vanadium, this is introduced in the form of oxideor sodium vanadate.

Other elements are sometimes present as impurities in the batchmaterials used for manufacturing the glass according to the invention(for example, manganese oxide in proportions of about 100 to 300 ppm),whether in the natural materials, in the recycled glass or in thescoria, but when the presence of these impurities does not give to theglass properties lying outside the limits defined above, these glassesare regarded as being in accordance with the present invention.

The present invention will be illustrated by the following specificexamples of optical properties and compositions.

EXAMPLES 1 TO 74

Table I gives, by way of indication, the base composition of the glassand the constituents of the glass batch to be melted in order to producethe glasses according to the invention. The glass batch may, ifnecessary, contain a reducing agent such as coke, graphite or slag, oran oxidizing agent such as a nitrate. In this case, the proportions ofthe other materials are modified so that the composition of the glassremains unchanged.

Tables IIa and IIb give the optical properties and the proportions byweight of the coloring agents of a glass containing respectively eithervanadium or chromium among its coloring agents. These proportions aredetermined by X-ray fluorescence of the glass and are converted into themolecular species indicated.

TABLE I Composition of Constituents of the base glass the base glassSiO₂ 71.5 to 71.9% Sand 571.3 Al₂O₃  0.8% Feldspar  29.6 CaO  8.8% Lime 35.7 MgO  4.2% Dolomite 167.7 Na₂O 14.1% Na₂CO₃ 188.6 K₂O  0.1% Sulfate 6.1 SO₃  0.1 to 0.5%

TABLE IIa Example 1 2 3 4 5 6 7 8 9 10 Fe₂O₃ (%) 0.79 0.80 0.78 0.860.87 0.87 0.93 0.93 0.94 0.79 FeO (%) 0.20 0.19 0.19 0.23 0.21 0.22 0.240.23 0.23 0.22 Co (ppm) 9 9 12 16 13 15 15 13 12 4 V₂O₅ (ppm) 169 322348 124 277 473 121 283 382 81 TLA4 (%) 68.20 67.75 67.32 63.87 64.2563.35 62.46 62.60 61.99 69.18 TE4 (%) 44.30 44.80 44.20 40.2 41.4 40.638.7 39.4 39 42.9 λ_(D) * (nm) 494.0 496.4 497.3 492.1 495.0 495.0 493.1496.2 496.8 495.4 P * (%) 6.49 5.64 5.55 8.41 6.82 7.05 8.18 6.68 6.646.2 TUV4 (%) 17.90 15.80 15.20 16.1 13.9 13.5 14.1 12.3 11.8 18.8 SE 1.51.5 1.5 1.6 1.6 1.6 1.6 1.6 1.6 1.6 Example 11 12 13 14 15 16 17 18 1920 Fe₂O₃ (%) 0.80 0.80 0.79 0.79 0.80 0.94 0.97 0.97 0.85 0.84 FeO (%)0.20 0.20 0.22 0.20 0.20 0.24 0.24 0.24 0.20 0.21 Co (ppm) 4 4 15 15 124 4 4 4 4 V₂O₅ (ppm) 279 377 105 365 360 76 268 401 106 333 TLA4 (%)68.94 68.49 65.14 64.96 65.23 65.72 65.00 64.12 68.80 67.43 TE4 (%) 43.943.6 41.7 42.5 43.1 39.7 39.5 38.8 43.8 42.8 λ_(D) * (nm) 499.5 500.6491.4 492.9 494.6 498.2 502.9 503.5 498.3 499.4 P * (%) 4.92 4.8 8.547.64 6.7 5.83 4.91 4.93 5.08 5.12 TUV4 (%) 16.2 15.6 18.1 16.4 15 13.911.8 11.1 16 14.6 SE 1.6 1.6 1.6 1.5 1.5 1.7 1.6 1.7 1.6 1.6 Example 2122 23 24 25 26 27 28 29 30 Fe₂O₃ (%) 0.84 0.85 0.85 0.85 0.84 0.85 0.860.86 0.88 0.86 FeO (%) 0.19 0.21 0.19 0.21 0.22 0.21 0.22 0.21 0.20 0.22Co (ppm) 4 8 8 9 5 4 4 21 42 23 V₂O₅ (ppm) 510 92 390 532 89 290 439 188183 270 TLA4 (%) 68.22 67.19 67.20 65.85 67.81 67.71 66.61 62.72 57.4462.25 TE4 (%) 44.1 42.5 43.9 41.9 41.6 42.8 41.7 40.8 39.5 40.2 λ_(D) *(nm) 504.4 496.0 500.9 499.3 496.8 501.6 502.5 492.9 488.5 493.0 P * (%)4.11 6.05 4.56 5.35 5.93 4.65 4.73 7.93 11.62 8.15 TUV4 (%) 13.4 15.913.6 13.5 16.4 14 13.1 14.2 13.4 13.9 SE 1.5 1.6 1.5 1.6 1.6 1.6 1.6 1.51.5 1.5 Example 31 32 33 34 35 36 37 38 39 40 Fe₂O₃ (%) 0.89 0.88 0.870.83 0.85 0.83 0.84 0.85 0.85 0.83 FeO (%) 0.21 0.21 0.21 0.20 0.20 0.200.21 0.20 0.20 0.22 Co (ppm) 2 4 7 2 3 4 2 4 5 12 V₂O₅ (ppm) 94 162 385276 274 264 471 421 445 92 TLA4 (%) 68.47 67.31 65.49 69.02 68.35 67.9667.92 68.23 67.20 65.78 TE4 (%) 42.50 41.90 41.30 43.80 43.60 43.6042.50 43.80 42.90 41.30 λ_(D) * (nm) 500.4 500.7 501.3 504.4 502.5 500.6502.1 503.8 500.5 493.3 P * (%) 4.80 4.90 5.04 4.05 4.35 4.72 4.65 4.214.90 7.50 TUV4 (%) 15.00 14.00 12.60 14.10 14.00 14.30 14.4 13.60 14.0016.70 SE 1.61 1.61 1.59 1.58 1.57 1.56 1.60 1.56 1.57 1.59 Example 41 4243 44 45 46 47 48 49 50 Fe₂O₃ (%) 0.84 0.84 0.83 0.83 0.86 0.86 0.860.85 0.86 0.86 FeO (%) 0.22 0.21 0.20 0.21 0.21 0.21 0.23 0.22 0.21 0.20Co (ppm) 12 12 21 22 14 14 11 87 16 13 V₂O₅ (ppm) 208 401 401 358 209184 200 195 161 158 TLA4 (%) 65.39 64.63 63.26 62.30 65.00 65.27 64.8647.74 64.33 65.91 TE4 (%) 41.30 41.50 41.50 40.70 41.40 41.90 40.5035.00 41.30 42.60 λ_(D) * (nm) 494.3 496.1 492.7 493.0 495.5 495.4 495.0483.5 494.4 496.5 P * (%) 7.09 6.44 7.95 8.07 6.52 6.47 6.92 20.89 7.015.88 TUV4 (%) 15.70 13.90 14.70 13.90 14.70 14.90 15.10 14.50 14.7014.40 SE 1.58 1.56 1.52 1.53 1.57 1.56 1.60 1.36 1.56 1.55 Example 51 5253 54 55 56 57 58 59 60 Fe₂O₃ (%) 0.87 0.87 0.85 0.96 0.87 0.88 0.860.86 0.84 0.85 FeO (%) 0.21 0.23 0.21 0.22 0.22 0.22 0.21 0.21 0.23 0.22Co (ppm) 13 13 16 12 10 12 11 16 12 12 V₂O₅ (ppm) 158 163 279 195 180229 200 204 195 278 TLA4 (%) 65.36 64.08 64.99 65.05 65.01 64.42 65.7964.18 64.68 64.52 TE4 (%) 41.70 39.70 41.70 41.20 41.20 40.60 42.0041.10 40.40 40.50 λ_(D) * (nm) 495.9 494.2 495.0 494.7 495.7 495.8 496.1494.1 493.7 494.5 P * (%) 6.28 7.43 6.68 6.90 6.49 6.58 6.16 7.22 7.557.12 TUV4 (%) 14.60 15.00 14.80 15.20 14.50 14.00 14.70 14.60 15.8014.90 SE 1.57 1.61 1.56 1.58 1.58 1.59 1.57 1.56 1.60 1.59

TABLE IIb Example 61 62 63 64 65 66 67 Fe₂O₃ (%) 0.93 0.93 1.02 1.020.84 0.84 0.93 FeO (%) 0.23 0.23 0.25 0.25 0.21 0.22 0.23 Co (ppm) 14 1515 15 15 15 14 Cr₂O₃ (ppm) 22 51 29 56 27 54 22 TLA4 (%) 63.77 63.2361.58 61.20 66.04 65.22 63.77 TE4 (%) 39.40 39.05 37.00 36.86 42.2741.31 39.40 λ_(D) * (nm) 494.1 495.5 495.8 497.1 493.4 494.1 494.1 P *(%) 7.49 7.20 7.31 6.96 7.26 7.41 7.49 TUV4 (%) 15.25 14.94 12.64 12.4617.52 17.73 15.25 SE 1.62 1.62 1.66 1.66 1.56 1.58 1.62 Example 68 69 7071 72 73 74 Fe₂O₃ (%) 0.93 1.02 1.02 0.84 0.84 0.93 0.94 FeO (%) 0.230.25 0.25 0.21 0.21 0.23 0.22 Co (ppm) 15 15 15 15 15 46 45 Cr₂O₃ (ppm)51 29 56 27 54 38 62 TLA4 (%) 63.23 61.58 61.20 66.04 65.22 55.71 55.97TE4 (%) 39.05 37.00 36.86 42.27 41.31 36.51 37.13 λ_(D) * (nm) 495.5495.8 497.1 493.4 494.1 487.9 488.8 P * (%) 7.20 7.31 6.96 7.26 7.4113.42 12.46 TUV4 (%) 14.94 12.64 12.46 17.52 17.73 14.85 14.33 SE 1.621.66 1.66 1.56 1.58 1.53 1.51

NB: *=expressed in SI at 5 mm under illuminant C.

What is claimed is:
 1. A green-colored soda-lime glass composed ofprinciple constituents-glass formers and of coloring agents,characterized in that the coloring agents consist of the followingpercentages by weight, the total amount of iron being expressed in theform of Fe₂O₃: Fe₂O₃  0.7 to 1.3% FeO 0.18 to 0.25% Co   0 to 0.0040%

and one of V₂O₅ 0.0050 to 0.15, or Cr₂O₃ 0.0015 to 0.0250%

and optional colorants present as batch impurities, and the glass has,under illuminant A and for a glass thickness of 4 mm, a lighttransmission (TLA4) of between 40 and 70%, a selectivity (SE4) ofgreater than or equal to 1.50, an ultraviolet radiation transmission(TUV4) of less than 20%, and a dominant wavelength (L_(D)) for a glassthickness of 5 mm of greater than 490 nm.
 2. The colored glass asclaimed in claim 1, characterized in that it has a selectivity (SE4) ofgreater than or equal to 1.55.
 3. The colored glass as claimed in claim1, characterized in that it has a selectivity (SE4) of greater than orequal to 1.60.
 4. The colored glass as claimed in claim 1, characterizedin that it has a light transmission of greater than 50%.
 5. The coloredglass as claimed in claim 1, characterized in that it has a lighttransmission of greater than 55%.
 6. The colored glass as claimed inclaim 1, characterized in that it has, for a glass thickness of 5 mm, adominant wavelength (λ_(D)) of less than 550 nm.
 7. The colored glass asclaimed in claim 1, characterized in that it has, for a glass thicknessof 5 mm, a dominant wavelength (λ_(D)) of less than 520 nm.
 8. Thecolored glass as claimed in claim 1, characterized in that it containsno more than three coloring agents.
 9. The colored glass claimed inclaim 1, characterized in that it has at least one of the followingoptical properties: 55%<TLA4<70% 30%<TE4<45% 6%<TUV4<20% 490nm<λ_(D)<520 nm 2%<P<10%.
 10. The colored glass as claimed in claim 1,characterized in that it has at least one of the following opticalproperties: 63%<TLA4<67% 37%<TE4<41% 11%<TUV4<18% 500 nm<λ_(D)<505 nm4%<P<6%.
 11. The colored glass as claimed in claim 1, characterized inthat it comprises the following percentages by weight of coloringagents, the total amount of iron being expressed in the form of Fe₂O₃:Fe₂O₃ 0.88 to 0.98% FeO 0.22 to 0.25%

and one of the following combinations: Co 0.0003 to 0.0009% plus V₂O₅0.0200 to 0.0400%, or Co 0.0003 to 0.0011% plus Cr₂O₃ 0.0020 to 0.0100%.12. The colored glass as claimed in claim 1, characterized in that ithas, for a thickness of 5 mm, a light transmission under illuminant C(TLC5) of between 50 and 70%.
 13. The colored glass as claimed in claim1, characterized in that it is coated with a layer of metal oxides. 14.The colored glass as claimed in claim 1, characterized in that it is insheet form.
 15. The colored glass as claimed in claim 1, characterizedin that it forms a window for an automobile.